Science Topics

Cosmology: The Study of the Universe and its Origins

Looking for the big picture? It doesn’t get any bigger than cosmology: the science of how the universe began and developed. What is it made of? How is it structured? What is its eventual fate, billions of years in the future? Supercomputer models and observations from ever-larger telescopes on the ground and in space have transformed cosmology into a predictive science, providing evidence that the universe is expanding at an ever-increasing rate, propelled by a mysterious pressure called “dark energy.” The Hayden Planetarium Space Show Dark Universe explores this new age of cosmic discovery.

Wondering what the March 2014 story about the Big Bang theory means for our knowledge of our universe? Or why you’re suddenly reading about “inflation” in a story about astrophysics? And just what are “cosmic ripples”?

Wondering what the March 2014 story about the Big Bang theory means for our knowledge of our universe? Or why you’re suddenly reading about “inflation” in a story about astrophysics? And just what are “cosmic ripples”?

Dark Universe, the new Hayden Planetarium Space Show premiering November 2, 2013, at the American Museum of Natural History, is produced by an acclaimed team that includes astrophysicist and curator Mordecai-Mark Mac Low. Here, Dr. Mac Low gives an overview of what we know about dark matter.

In 1998, two independent teams of astrophysicists discovered a baffling phenomenon: the Universe is expanding at an ever-faster rate. The current understanding of gravity can't explain this cosmic acceleration. Scientists think that either a mysterious force called dark energy is to blame—or a reworking of gravitational theory is in order.

In 1998, two independent teams of astrophysicists discovered a baffling phenomenon: the Universe is expanding at an ever-faster rate. The current understanding of gravity can't explain this cosmic acceleration. Scientists think that either a mysterious force called dark energy is to blame—or a reworking of gravitational theory is in order. Travel to the University of California's Lick Observatory to learn how astrophysicists use distant stellar explosions to observe the expansion of space. Then watch a team at Fermilab assemble the Dark Energy Camera, a new device researchers hope will find compelling evidence of what's propelling the Universe to expand at an increasing pace.

In the 1920s in California, astronomer Edwin Hubble observed distant galaxies using an extremely powerful telescope. He made two mind-boggling discoveries.

First, Hubble figured out that the Milky Way isn’t the only galaxy. He realized that faint, cloud-like objects in the night sky are actually other galaxies far, far away. The Milky Way is just one of billions of galaxies.

Second, Hubble discovered that the galaxies are constantly moving away from each other.In other words, the universe is expanding. The biggest thing that we know about is getting bigger all the time.

A few years later,Belgian astronomer Georges Lemaître used Hubble‘s amazing discoveries to suggest an answer to a big astronomy question: “How did the universe begin?”

According to the Big Bang theory, the expansion of the observable universe began with the explosion of a single particle at a definite point in time. This startling idea first appeared in scientific form in 1931, in a paper by Georges Lemaître, a Belgian cosmologist and Catholic priest.

According to the Big Bang theory, the expansion of the observable universe began with the explosion of a single particle at a definite point in time. This startling idea first appeared in scientific form in 1931, in a paper by Georges Lemaître, a Belgian cosmologist and Catholic priest.

The theory, accepted by nearly all astronomers today, was a radical departure from scientific orthodoxy in the 1930s. Many astronomers at the time were still uncomfortable with the idea that the universe is expanding. That the entire observable universe of galaxies began with a bang seemed preposterous.

Imagine if your digital camera was scaled to the size of a dishwasher. And weighed about 135 kilograms. And cost about $5 million to build. At its barest bones, the Sloan telescope is an outsize digital camera, but one sophisticated enough to capture every luminous object (about 200 million) in large, contiguous swaths of the northern celestial hemisphere. Its goal is to build up an exquisitely detailed picture of the structure of the Universe

According to Einstein, you need to describe where you are not only in three-dimensional space* — length, width and height — but also in time. Time is the fourth dimension. So to know where you are, you have to know what time it is.

According to Einstein, you need to describe where you are not only in three-dimensional space* — length, width and height — but also in time. Time is the fourth dimension. So to know where you are, you have to know what time it is.

Your complete answer should be "I'm sitting on a 4-foot-high aardvark at the northeast corner of Bern St. and Ulm St., and it's July 1st, 2002, at 1:23 p.m. on my watch." Einstein called a description that used four dimensions an event.

The year 2015 marked the 100th anniversary of Einstein’s publication of his general theory of relativity—a theory almost everyone has heard of, but few truly understand. In this podcast, astrophysicist and educator Jeffrey Bennett introduces the basic tenets of Einstein's theory, and underscores its importance to our modern understanding of the universe.

LIGO sensors picked up tiny ripples in space-time caused by a black hole merger that took place 1.3 billion years ago. It was the first direct evidence of gravitational waves, one century after they were predicted by Einstein’s theory of general relativity.

In science, there are questions, and there are Questions. Astronomers, in particular, want to know the structure of the Universe in detail. What is its arrangement today, and what did it look like at its birth? And how did we get from then to now? Theoreticians are particularly eager to know what exactly happened at the Universe’s first moment … and, of course, what came before that.

In the nearby Hyades star cluster, a pair of dead stars is surrounded by dust particles that resemble the building blocks of rocky planets. These particles allow astronomers to study the chemical makeup of planetary building material, and suggest that planet formation may take place even around burnt-out or failed stars.

He was a leading planetary astronomer, a pioneer in the search for extraterrestrial biology, a spellbinding teacher, and the most effective public advocate for the values of science the world has ever seen.

He was a leading planetary astronomer, a pioneer in the search for extraterrestrial biology, a spellbinding teacher, and the most effective public advocate for the values of science the world has ever seen. To hundreds of millions of people, Sagan communicated his passion for the universe of science. “When you’re in love,” he said, “you want to tell the world.”

One of the fundamental predictions of the Big Bang is the present day existence of relic neutrino produced less than one second after the event. Christopher Tully, professor of physics at Princeton University, discusses a new experiment called PTOLEMY (Princeton Tritium Observatory for Light, Early-Universe, Massive-Neutrino Yield) and its potential to challenge this core prediction, as well as uncover new properties of neutrinos themselves.

The composition of the universe is constantly changing. The universe began with hydrogen and helium. Through fusion in the stars and explosive supernovae other heavier elements were created from these two elements.

The composition of the universe is constantly changing. The universe began with hydrogen and helium. Through fusion in the stars and explosive supernovae other heavier elements were created from these two elements. Overtime more and more light elements were turned into heavier elements.

If you throw a ball into the air, it will return to the ground. Why? Earth has invisible pulling power called gravity. Every object in the universe-stars, planets, moons, even you - has gravity. Gravity is a force of attraction between all objects. Some things have lots of gravity, some have just a little.

If you throw a ball into the air, it will return to the ground. Why? Earth has invisible pulling power called gravity. Every object in the universe-stars, planets, moons, even you - has gravity. Gravity is a force of attraction between all objects. Some things have lots of gravity, some have just a little.

In 1687, a physicist and mathematician named Isaac Newton published a remarkable discovery. He figured out that the same force that causes an apple to fall to the ground also keeps the Moon in orbit around Earth.

In 1929, Edwin Hubble showed that the light from distant galaxies is shifted to longer wavelengths in proportion to their distances from the Milky Way. The modern interpretation is that space itself is expanding, carrying the galaxies along for the ride.

In 1929, Edwin Hubble showed that the light from distant galaxies is shifted to longer wavelengths in proportion to their distances from the Milky Way. The modern interpretation is that space itself is expanding, carrying the galaxies along for the ride.

In 1931, Georges Lemaître imagined running such an expansion backwards in time. At some remote point in the past, he reasoned, everything in the universe would have been packed together at enormous density. Lemaître suggested that all the matter and energy in the observable universe originated in an explosion of space, now called the Big Bang, which launched the expansion that continues to this day.

"In a spiral galaxy, the ratio of dark-to-light matter is about a factor of ten. That's probably a good number for the ratio of our ignorance-to-knowledge. We're out of kindergarten, but only in about third grade."

—Vera Rubin

For every visible star in the observable universe, there are nine masses that are invisible and unidentified. Learn more about the astronomer who proved the existence of dark matter.

Astronomers are investigating the new frontiers of dark matter and dark energy, critical to understanding the cosmos but of uncertain economic promise to society. In this 2014 lecture, Astrophysicist and scholar Martin Harwit addresses these current challenges in view of competing national priorities - and he proposes alternative new approaches to the search for the true Universe.

Neil deGrasse Tyson hosts and moderates a panel of experts in a lively discussion about the merits and shortcomings of a provocative and revolutionary idea—that perhaps the universe as we know it is a computer simulation. While the debate may have started as a science fiction speculation, it has become a serious line of investigation among physicists, astrophysicists, and philosophers.

The Cosmic Microwave Background (CMB) is a vast curtain of energy left over from the Big Bang. It is the oldest, most distant feature of the observable Universe. Since the discovery of the CMB in the mid-1960s, cosmology—the study of the origin and evolution of the Universe—has experienced an explosion of activity. The field has changed from a purely theoretical enterprise to the empirical study of what populates the physical Universe.